LOCATION PENZANCE           AZ
Established Series
Rev. AAD/PDC
01/2007

PENZANCE SERIES


The Penzance series consists of very deep, well drained soils that formed in fan alluvium. Penzance soils are on fan terraces and have slopes of 0 to 5 percent. The mean annual precipitation is about 8 inches and the mean annual air temperature is about 52 degrees F.

TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Haplargids

TYPICAL PEDON: Penzance clay loam - rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 3 inches; light reddish brown (5YR 6/3) clay loam, reddish brown (5YR 4/3) moist; weak thin platy structure parting to moderate very fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots, many very fine vesicular and few very fine and fine tubular pores; slightly effervescent, 9 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 5 inches thick)

Btn1--3 to 9 inches; light reddish brown (5YR 6/3) clay, reddish brown (5YR 4/3) moist; moderate fine subangular blocky structure; hard, firm, sticky and slightly plastic; many very fine and fine roots; few fine and very fine tubular and irregular pores; few faint clay films on faces of peds and lining pores; strongly effervescent, 11 percent calcium carbonate equivalent; slightly sodic (SAR 5); strongly alkaline (pH 8.6); clear smooth boundary.

Btn2--9 to 17 inches; light reddish brown (5YR 6/3) clay, reddish brown (5YR 4/3) moist; moderate medium subangular blocky structure; very hard, firm, sticky and plastic; many very fine and fine roots; few fine and very fine tubular and irregular pores; common faint clay films on faces of peds and lining pores; common stress surfaces; violently effervescent, 11 percent calcium carbonate equivalent; slightly sodic (SAR 10); strongly alkaline (pH 8.6); clear smooth boundary.

Btknz--17 to 32 inches; light reddish brown (5YR 6/3) clay, reddish brown (5YR 4/3) moist; moderate fine angular blocky structure; very hard, firm, very sticky and very plastic; few very fine and fine roots; few fine tubular and irregular pores; few faint clay films on faces of peds and lining pores; many stress surfaces; common fine, rounded, soft accumulations of calcium carbonate; violently effervescent, 11 percent calcium carbonate equivalent; slightly saline (ECe 5 dS/m) and slightly sodic (SAR 13); strongly alkaline (pH 8.6); clear smooth boundary. (Combined thickness of the Bt horizons is 25 to 45 inches)

Bssknz--32 to 42 inches; light reddish brown (5YR 6/3) clay, reddish brown (5YR 4/3) moist; moderate fine and very fine angular blocky structure; very hard, firm, very sticky and very plastic; few very fine roots; few fine tubular and irregular pores; common stress surfaces; few intersecting slickensides; few fine soft accumulations of calcium carbonate; violently effervescent, 10 percent calcium carbonate equivalent; slightly saline (ECe 5 dS/m) and slightly sodic (SAR 10); strongly alkaline (pH 8.6); clear smooth boundary.

Bssknzy--42 to 60 inches; reddish brown (5YR 5/3) clay, reddish brown (5YR 4/3) moist; moderate medium angular blocky structure; very hard, very firm, very sticky and very plastic; common intersecting slickensides; few fine soft accumulations of calcium carbonate; strongly effervescent, 1 percent calcium sulfate, 9 percent calcium carbonate equivalent; slightly saline (ECe 5 dS/m) and slightly sodic (SAR 12); strongly alkaline (pH 8.6). (Combined thickness of the Bk horizons is 10 to 30 inches)

TYPE LOCATION: Navajo County, Arizona; about 17 miles northeast of Holbrook; center of section 2, T. 18 N., R. 23 E.

RANGE IN CHARACTERISTICS:

Soil Moisture - Intermittently moist in some part of the soil moisture control section during July-September and December-February. Driest during May and June. Typic aridic soil moisture regime.

Rock Fragments: Less than 10 percent

Soil Temperature: 55 to 58 degrees F.

Salinity: Nonsaline to slightly saline

Sodicity: Nonsodic to slightly sodic

Organic Matter: Less than 1 percent in the surface

Cracks when dry: Range from 1 to 2 cm wide and extend from the base of the surface horizon to 20 inches or more. Present for some period in all years.

A horizon
Hue: 5YR, 7.5YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3 or 4, dry or moist

Bt horizon
Hue: 5YR, 7.5YR
Value: 4, 5 or 6 dry, 3, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture: Clay loam, sandy clay, clay

Bss horizon
Hue: 5YR, 7.5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 6 dry, 3, 4 or 6 moist
Texture: Loam, sandy clay loam, clay loam, clay
Calcium carbonate: Less than 15 percent calcium carbonate equivalent that is disseminated or segregated
Gypsum: 0 to 2 percent

COMPETING SERIES: This is the Hinman (CO) series. Hinman soils have hue of 7.5YR or yellower.

GEOGRAPHIC SETTING: Penzance soils are on fan terraces of undulating plateaus at elevations of 4,500 to 5,500 feet. These soils formed in fan alluvium derived dominantly from mudstone and sandstone. Slopes range from 0 to 5 percent. The mean annual precipitation is 6 to 10 inches. The mean annual air temperature is 53 to 56 degrees F. The frost-free period is 150 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Grieta, Moffat and Sheppard soils. All contain less than 35 percent clay in the particle-size control section.

DRAINAGE AND PERMEABILITY: Well drained; slow runoff; slow permeability.

USE AND VEGETATION: Penzance soils are used for livestock grazing, recreation, and wildlife habitat. Present vegetation is alkali sacaton, black grama, galleta, blue grama, bottlebrush squirreltail, fourwing saltbush, and broom snakeweed.

DISTRIBUTION AND EXTENT: Northeast Arizona. This series is of small extent. MLRA 35.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Navajo County, Arizona; Soil survey of Navajo County Area, Arizona, Central Part; 1994.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - The zone from 0 to 3 inches (A horizon)

Argillic horizon - The zone from 3 to 32 inches (Btn1, Btn2, Btknz horizons)

Vertic subgroup - Cracks within 50 inches that are 5mm or more wide and presence of slickensides

Cracks filled with eolian sands observed to a depth of 32 inches

ADDITIONAL DATA: NSSL Sample S86AZ-17-1


National Cooperative Soil Survey
U.S.A.